OSE Faculty, Dr. Jean-Claude Diels gives an invited paper on Sub-nano-scale phase sensing and improvement by squeezing

Departmental News

Prof. Jean-Claude Diels

Posted: February 1, 2023


Extreme sensitivity in measuring minute changes are traditionally achieved by marvels of techology, such as high finess (10E5) Frabry Perots, probed with laser of only 1 Hz linewidth, and complex electronics. It is shown that the same result can be obtained with standard unstabilized lasers emitting dual frequency combs. The source of combs has a coherence time in the microsecond range, yet a mutual coherence time between the combs of 100 s is achieved. The traditional approach to produce correlated beams is to split a cw beam into two components shifted in frequency and angularly separated by an acousto-optic modulator (AOM). The beat signal obtained by interfering with the two beams has a bandwidth related to the noise in the AOM, which is typically driven in the 1 to 100 MHz range. Another contribution to the beat note bandwidth arises from the coherence time of the beam, as compared to the period of modulation. Our approach to create correlated optical beams is to insert an electro-optic phase modulator inside a mode-locked Optical Parametric Oscillator (OPO) operating with two pulses circulating in its cavity, producing two interwoven frequency combs. With the phase modulator driven at the OPO cavity round-trip frequency the two combs can be shifted in frequency. While the bandwidth of each of the combs is in the MHz range, they can be interfered with to produce a beat note of 0.01 Hz bandwidth, indicating a high level of correlation between these two combs. Each pair of pulses inside the cavity is given opposite phase shift, in a time interval shorter than 10 ns, a time too short to experience a significant classical noise. In one example of measurement, the mean square deviation of the phase difference imparted on the two pulses is 0.4 · 10−9, corresponding to a phase-photon number uncertainty product of 0.66. Some sensing applications will be proposed.

Authors: Prof. Jean-Claude Diels, University of New Mexico, OSE, Department of Physics and CHTM


Jean-Claude Diels started his career in Research constructing a CO2 laser as part of his one-year military service (too long) in Belgium. He went then for 5 years (much too long) as a Research Scientist in the Fundamental Research Laboratories of ”Philips Gloelampenfabrik” in Eindhoven, with assignment to ”do modern research” and given an “unlimited budget” (which was soon exceeded). He spent the next 3 years (way too short) to do Ph.D. thesis research on coherent pulse propagation in two level systems with Professor Erwin L. Hahn at UC Berkeley. The next two years (too long) were spent at the Max Plank Institute with Professor Fritz Schaefer, the colorful (usually covered with red) father of dye lasers. He got an appointment as Research Assistant - then Associate - Professor at the University of Southern California (”What??? I have to raise my own salary?”). After some experience at the” Centre d’Energie Atomique” of Saclay near Paris (not the Texan Paris), and before the collapse of the Center for Laser Studies at USC, he moved to the CAQE (Center for Applied Quantum Electronics) of the University of North Texas in Denton, where he stayed for 5 years (too long), interrupted by (a breath of fresh air) a sabbatical at the University of Bordeaux, France. He has been since (much, much, much too long) at the University of New Mexico, where he graduated some 60 PhD students. He co-authored with Wolfgang Rudolph the graduate textbook “Ultrashort Laser Pulse Phenomena: Fundamentals, Techniques and Applications on a Femtosecond Time Scale” and is still struggling to complete a 3rd edition. Another books is “Lasers: The Power and Precision of Light”, (co-author Ladan Arissian) to celebrate the 50th anniversary of the laser. More recently he edited the book “Light Filaments Structures, challenges and applications” (published December 2021). He is the recipient of the 51st Annual Research Lecturer Award (April 2006), and of the 2006 Engineering Excellence Award of the Optical Society of America. 

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